Why shouldn't I connect my Prosody X card to an ethernet hub?

An ethernet hub merely acts as a repeater, which means that it receives a packet on a port, it immediately transmits that packet on all other ports. This means that bandwidth on each port is wasted by the needless transmission of unicast packets that are in fact destined for devices on other ports

The theory is that a half duplex ethernet will become saturated at around a third of its theoretical bandwidth limit, although this figure is heavily dependent on the characteristics of the data on the network.

This unpredictable reduction in bandwidth means that hubs are unsuitable for high performance systems like Prosody X.